DRAFT 

DISCUSSION POINTS REGARDING RECONSTRUCTING 

LOCALIZED SKIN DOSE ASSOCIATED WITH DIRECT 

DEPOSITION OF URANIUM OXIDE DUST AND FLAKES ON 

EXPOSED SKIN 

Contract No. 200-2009-28555 

Revision 0 

Prepared by 

John Mauro, PhD, CHP 

U. Hans Behling, PhD, MHP 

SC&A, Inc. 

1608 Spring Hill Road, Suite 400 

Vienna, VA 22182 

June 2013 

Disclaimer 

This document is made available in accordance with the unanimous desire of the Advisory Board 

on Radiation and Worker Health (ABRWH) to maintain all possible openness in its 

deliberations. However, the ABRWH and its contractor, SC&A, caution the reader that at the 

time of its release, this report is pre-decisional and has not been reviewed by the Board for 

factual accuracy or applicability within the requirements of 42 CFR 82. This implies that once 

reviewed by the ABRWH, the Board’s position may differ from the report’s conclusions. Thus, 

the reader should be cautioned that this report is for information only and that premature 

interpretations regarding its conclusions are unwarranted.
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S. COHEN & ASSOCIATES:

Technical Support for the Advisory Board on

Radiation & Worker Health Review of

NIOSH Dose Reconstruction Program

Document No. 

Reconstructing Localized Skin Dose

Effective Date: 

Draft – June 12, 2013

Discussion Points Regarding Reconstructing 

Localized Skin Dose Associated with Direct 

Deposition of Uranium Oxide Dust and Flakes 

on Exposed Skin

Page 2 of 15

Task Manager/Reviewer:

________________________ Date: ___________

John Mauro, PhD, CPH

Supersedes:

N/A

Project Manager:

________________________ Date: ___________

John Stiver, MS, CHP

Reviewer(s):

 

 John Stiver

Record of Revisions

Revision 

Number

Effective 

Date Description of Revision

0 (Draft) 06/12/2013 Initial issue
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TABLE OF CONTENTS

Abbreviations and Acronyms ..........................................................................................................4

1.0 Introduction..........................................................................................................................5

2.0 Background..........................................................................................................................5

3.0 Description of the Issues......................................................................................................6

4.0 SC&A’s Current Position on NIOSH’s Proposed Dose Models.........................................7

5.0 Concerns Related to NIOSH’s Dose Model for Chronic Deposition of Fine 

Particles on Bare Skin..........................................................................................................7

5.1 Selection of Model Parameters................................................................................7

5.2 Dose to Exposed Skin ..............................................................................................7

5.3 SC&A’s Response ...................................................................................................8

6.0 Concerns Related to How IREP Derives POC and Its Relevance to How Dose Is 

Assigned.............................................................................................................................10

7.0 Concerns Related to NIOSH’s Dose Model for Large Uranium Flakes on Skin ..............11

8.0 References..........................................................................................................................11

Appendix A: Excerpt from the Report, Reassessment of Acute Radiation Dose Associated 

with BRAVO Fallout ..........................................................................................................13
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ABBREVIATIONS AND ACRONYMS

AMAD activity median aerodynamic diameter

AWE Atomic Weapons Employer

CFR Code of Federal Regulations

cm2square centimeter

d/yr day per year

dpm disintegrations per minute

DR dose reconstruction

ERR excess relative risk

FEMP Fernald Environmental Management Project

GM geometric mean

GSD geometric standard deviation

hr or h hour

IREP Interactive RadioEpidemiological Program

m

2

square meter(s)

m

3

cubic meter(s)

MeV mega-electron volt

mg milligram

mR milliroentgen

mrad millirad

mrem millirem

m/s meter(s) per second

NIOSH National Institute for Occupational Safety and Health

PHS U.S. Public Health Service

POC or PC probability of causation

SC&A S. Cohen and Associates (SC&A, Inc.)

Sv sievert

TBD Technical Basis Document
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1.0 INTRODUCTION

During our Dose Reconstruction (DR) Subcommittee meeting on May 21, 2013, issues were 

raised regarding a mini site profile review that was performed for Bridgeport Brass (i.e., 

Attachment 1 to the 8th set of DR reviews). The issues pertained to reconstructing the doses to 

skin (i.e., Finding 3) and associated probabilities of causation (POCs), due to the deposition of 

particles/flakes of uranium oxide on exposed skin (i.e., hands, forearms, face, neck, and ears).

The discussions addressed the plausibility of such a scenario and, given that the scenario is 

considered plausible, what methods would be used to derive doses for use as input to IREP.

After a brief discussion of this matter, the Subcommittee concluded that this is a generic issue 

and is appropriately transferred to a work group dealing with overarching issues.

Subsequent to that discussion, SC&A revisited the issue, and we have a better understanding of 

the approach NIOSH has adopted to address localized skin dose. However, we still have some 

questions that warrant discussion. On May 29, 2013, SC&A sent an e-mail to our Project Officer 

requesting authorization to prepare a brief white paper on this matter, the objective of which 

would be to help expedite the resolution of these issues. On May 29, 2013, our Project Officer 

authorized SC&A to proceed with the preparation of a white paper on this subject. This report 

presents that white paper.

2.0 BACKGROUND

Issues pertaining to localized exposure of skin due to the deposition of uranium oxide flakes on 

bare skin were raised by SC&A during the review of numerous site profiles and DRs dealing 

with uranium metal machining, rolling, and general handling at Atomic Weapons Employer

(AWE) facilities during the early years of the atomic weapons program, mainly the mid to late 

1940s and the early 1950s. Examples of such facilities include Bethlehem Steel and Simonds 

Saw and Steel. Our review of these types of AWE site profiles and DRs indicates to us that such

a scenario was plausible and needed to be addressed in the DRs for claimants who worked at 

these facilities in the early years and contracted skin cancer on the face and neck and other 

unprotected areas of the skin. We believe that such scenarios were inevitable because workers at 

that time did not wear protective clothing and were not monitored for contamination when 

leaving a work area. Hence, such exposures could/would have occurred on a daily basis in the 

workplace. We note that our reviews of numerous AWE site profiles and DRs include the 

assessment of skin exposures, but only from the perspective of beta exposure at a distance; e.g., 

skin exposures attributable to standing next to uranium metal ingots, or exposure to nonpenetrating radiation as determined by the use of film badges. We have not encountered any site 

profiles or DRs where exposures due to direct contamination of localized areas of skin with 

uranium dust or uranium oxide flakes were evaluated.

During the May 21, 2013, DR Subcommittee meeting, both NIOSH and some Advisory Board 

members expressed concern regarding the credibility of such a scenario. SC&A agreed that, in 

the absence of monitoring data, we do not have the means to quantify skin doses. However, the 

presence of airborne radioactivity as evidenced by air sampling data leads to the conclusion that

skin contaminations were inevitable.
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3.0 DESCRIPTION OF THE ISSUES

During the May 21, 2013, meeting, some progress was made in exploring this issue before the 

Subcommittee determined that this subject is generic and is best transferred to an overarching 

issues work group. As such, it is appropriate to describe the technical discussions that took place 

at the meeting before those discussions were terminated. 

During the meeting, NIOSH described and provided written material explaining how they would 

go about reconstructing localized skin doses at facilities such as Bridgeport Brass and Harshaw 

Chemical Company, which, in turn, would be used as input to IREP for the purpose of deriving 

POCs. The following is the description provided by NIOSH for reconstructing the skin dose for 

Bridgeport Brass:

An assessment was made to determine the skin dose from routine skin 

contamination associated with uranium operations. Based on the Technical Basis 

Document: An Exposure Matrix for Bridgeport Brass: Havens Laboratory and 

Adrian Plant (ORAUT-TKBS-0030 Rev. 01) [ORAUT 2013], the geometric mean 

of the Table 3-5 individual daily weighted-average air concentration is 250 

dpm/m3 with a geometric standard deviation of 2.2. This results in a 95th

percentile air concentration of 915 dpm/m3. Assuming a terminal settling velocity 

of 0.00075 m/s and 8 hours of operations, a constant air concentration of 

915 dpm/m3 would result in a surface contamination level of 1.98 dpm/cm2. One 

could assume that the skin of the head, neck, and hands were re-contaminated at 

the same level of general surfaces every workday (250 workdays) of the year. The 

skin on the head, neck, and hands represent about 14% of the total body skin 

area. A maximizing skin dose rate of 40 mrem per 10,000 dpm/cm2per hour can 

be applied to determine the skin dose to the affected area (Technical Basis for 

Beta Skin Dose Calculations at the Y12 Plant, SRDB 19821) [Thomas and Bogard 

1994]. This would result in a dose to the affected skin of about 16 mrem. Per 

guidance in Interpretation of Dosimetry Data For Assignment of Shallow Dose 

(ORAUT-OTIB-0017 Rev. 01) [ORAUT 2005], the 16 mrem to the affected skin 

could be converted to the dose to the skin based on the described approach for 

non-uniform exposures, resulting in a geometric mean annual skin dose of about 

2 mrem with a geometric standard deviation of 8. As a note, this is a bounding 

estimate using a maximizing skin dose rate and contamination levels. A more 

realistic skin dose rate and the use of the geometric mean air concentration would 

result in an exposure of less than 1 mrem.

During the meeting, SC&A questioned this approach for deriving annual skin dose for a scenario 

where the exposed skin is contaminated by the settling of 5 micron AMAD particles on surfaces 

during the course of a working day. SC&A also questioned the scenario involving the deposition 

of large flakes of uranium oxide on bare skin. This scenario is somewhat different than that 

described and modeled by NIOSH, in that the particles could be much thicker and deliver a 

relatively high dose rate to very small areas of the skin. For example, a flake of uranium oxide 

could deliver a skin dose approaching 240 mrem/hr beneath the flake. Notwithstanding the 

plausibility of such a scenario, we explained that we were uncertain how the input to IREP 
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would be defined that yields a claimant-favorable POC. It is at this point where it was agreed to 

transfer the issue to an overarching issues resolution work group.

4.0 SC&A’S CURRENT POSITION ON NIOSH’S PROPOSED DOSE MODELS

Following the meeting, SC&A had an opportunity to further assess NIOSH’s approach, as 

described above. It appears that NIOSH’s strategy for deriving skin dose from the settling of 

fine particles on skin may be incomplete, as well as underestimate potential doses. We have 

several questions/concerns that we would like to introduce at the next work group meeting where 

this topic is on the agenda. The following presents SC&A’s questions/concerns regarding (1) the 

exposure scenario where a fine dust settles on exposed skin during the course of a work day, 

(2) the deposition of a single large flake of uranium oxide on exposed skin, and (3) is NIOSH’s 

approach to deriving POCs for this class of problem appropriate given IREP in its current form?

5.0 CONCERNS RELATED TO NIOSH’S DOSE MODEL FOR CHRONIC 

DEPOSITION OF FINE PARTICLES ON BARE SKIN

5.1 Selection of Model Parameters

As summarized in the above-stated quotation, NIOSH’s model for deriving skin doses at 

Bridgeport Brass employs the following values and assumptions for deriving skin dose and 

cancer risk:

 A geometric mean (GM) of a daily weighted-average air concentration of 250 dpm/m3

with a geometric standard deviation (GSD) of 2.2 yielding a 95th percentile air 

concentration of 915 dpm/m3;

 A terminal settling velocity of 0.00075 m/s;

 An 8-hour per day facility operation;

 A 250 days per year work schedule during which daily recontamination takes place on 

the head, neck, and hands, representing 14% of the 18,000 cm2of total skin for males (or 

16,000 cm2of total skin for females); and

 A skin contamination conversion factor of 40 mrem per hour per 10,000 dpm/cm2.

5.2 Dose to Exposed Skin

Daily Skin Contamination = (915 dpm/m3)(0.00075 m/s)(m2/10,000 dpm/cm2)(3,600 s/h)(8 h)

 = 1.98 dpm/cm2

Skin Dose Rate = (1.98 dpm/cm2)(40 mrem/h/10,000 dpm/cm2)

 = 7.92 x 10-3 mrem/h

Yearly Skin Dose = (0.008 mrem/h)(8 h/d)(250 d/yr)

 = 16 mrem/yr
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For a “non-uniform” skin contamination exposure that involves 14% of the skin, NIOSH reduced 

the 16 mrem/yr skin dose to 2 mrem/yr for deriving a POC value. The purpose of this 8-fold 

dose reduction is to offset the radiation skin cancer risk coefficient used by IREP, which is based 

on total (i.e., 100%) skin exposure.

5.3 SC&A’s Response

The derived dose of 16 mrem/yr to bare skin is based on unsupported and unrealistic 

assumptions, which include the following:

(1) Daily skin contaminations for each of the 250 workdays per year that only persist for 

8 hours;

(2) Implication that after 8 hours, each skin contamination is 100% removed by a standard 

daily shower; and

(3) Only bare skin is subject to contamination and resultant radiation exposure.

Exposure Duration. While select facilities may have provided end-of-shift showering facilities 

for their workers, others may not; but even for facilities with showering facilities, there is no 

assurance that workers would have consistently made use of such a facility. A more 

conservative assumption may involve a daily morning (i.e., before work) shower, which would 

imply that daily skin contamination would remain up to 24 hours instead of the 8 hours assumed 

by NIOSH.

Decontamination Efficiency. The assumption that skin contamination is readily and completely

removed by a routine shower is unrealistic. Experience shows that skin contaminations 

commonly require multiple and focused washings with specific agents before significant 

reduction of contaminants is observed. For chronic exposures/contamination events, a buildup to 

a steady-state of residual skin contaminants must reasonably be expected.

Skin Contamination Other than to Bare Skin. NIOSH’s assumption that only bare skin 

(representing 14% of total skin) is subject to contamination/radiation exposure from the 

deposition of airborne activity is unrealistic. This is particularly true for work environments 

involving heavy physical activity, worker perspiration, and damp clothing. Thus, any deposition 

of airborne contaminants (as well as contact with existing contaminated surfaces in the 

workplace) by clothing worn by a worker must reasonably be assumed to become contaminated, 

and that, at a minimum, the level of contamination is comparable to that of bare skin. In 

Section 6.3.4.2 of Feed Materials Production Center site profile (ORAUT 2004), NIOSH 

provides the following guidance for determining the skin dose under clothing from exposure to 

uranium.

Results of tests of FEMP dosimeters used during the 1960s (Heatherton 1960) 

included the conclusion that the half-value thickness of absorption of UX-2 

(

234Pa) beta energy was approximately 110 mg/cm2

. It was determined that “the 

combined dose rate from the surface of uranium metal in equilibrium with its two 

daughters, UX-1 (234Th) and UX-2 (234Pa), is about 240 mrad/hr.” It was also 
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determined that approximately 95% of the surface dose rate, or approximately 

228 mrad/hr, originated from the UX-2 in the metal . . . It was also determined 

that coveralls worn by workers (about 30 mg/cm

2

) reduced uranium beta 

exposure to the skin by approximately 20%. Figure 6-6, at the end of this TBD, 

summarizes these data. [Emphasis added.]

Figure 6-6. Beta Dose vs. Skin Depth

On the assumption that contamination on clothing equals the contamination level on bare skin, 

the “NIOSH-derived” dose of 16 mrem/yr for bare skin would yield a dose of about 13 mrem/yr 

for the balance of the 86% of “clothed” skin. It may further be argued that skin dose to clothed 

areas of the body may actually be higher than bare skin for the likely reason that workers may 

have worn contaminated clothing for multiple days before such clothing was subjected to the 

limited decontamination provided by home laundering.

In support of SC&A’s assertions about the limited effectiveness of even focused efforts to 

decontaminate skin and clothing apparel, empirical data are provided in the enclosed Appendix. 

These data were originally reported by Robert Sharp and William Chapman in the 1957 report 

titled, Exposure of Marshall Islanders and American Military Personnel to Fallout, and 

summarized by SC&A in a report to the Nuclear Claims Tribunal of the Republic of the Marshall 

Islands in 2000 (SC&A 2000).

Although activity levels associated with BRAVO fallout and those associated with airborne 

concentrations at AWE facilities differ by orders of magnitude, the issues raised by SC&A are, 

nevertheless, similar between the two scenarios.
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6.0 CONCERNS RELATED TO HOW IREP DERIVES POC AND ITS RELEVANCE 

TO HOW DOSE IS ASSIGNED

Given that a skin dose only occurs to a limited area, SC&A has concerns regarding the 

relationship between the derived dose and how IREP uses this dose to derive a POC. It is our 

understanding that a POC is derived by evaluating the probability that a given cancer was caused 

by a given exposure to ionizing radiation, as opposed to being caused by the myriad other factors 

that might be responsible for causing that cancer. Hence, in its simplest form, as described in

42 CFR Part 81, the equation used to derive POC is as follows:

RadRisk/(RadRisk + BasRisk) × 100% = PC

RadRisk refers to the probability that a given dose of radiation to an organ can cause a given type 

of cancer, and BasRisk refers to the baseline probability of that type of cancer. The actual 

equation is a lot more complicated because it takes into consideration the age at time of 

exposure, the age at time of diagnosis, gender, the number of annual exposures up to the time 

that the cancer is diagnosed, and other factors, as appropriate, such as race in the case of skin 

cancer and smoking in the case of lung cancer. To further complicate matters, the entire 

calculation is performed using probability distributions as input, so that the POC can be reported 

in terms of the 99% confidence level. Fortunately, all these complications do not come into play 

with respect to SC&A’s questions. SC&A’s questions have to do with the linkage between the 

organ doses that are used as input to IREP and the baseline risk that is imbedded in IREP for the 

purpose of deriving the POC associated with a given skin exposure.

Under most circumstances when skin exposure is of concern, the exposure occurs at a distance. 

An example would be standing close to a slab of uranium where, more or less, the entire body is 

exposed to both penetrating and non-penetrating radiation. Hence, the dose that is input to IREP 

for the purpose of deriving the POC for a skin cancer is the dose experienced by the individual to 

all the skin and, under these circumstances, the baseline risk is the baseline risk of developing a 

given type of skin cancer. 

Given this understanding, let us return to the NIOSH explanation of the approach used to derive 

the POC for a scenario where a portion of the skin is exposed. NIOSH explains that, in order to 

derive the POC, it is necessary to average the exposure over the entire area of the skin. 

Specifically, the skin on the head, neck, and hands represents about 14% of the total body area of 

the skin area. Hence, the derived localized skin dose of 16 mrem/yr is reduced to a GM of 

2 mrem/year with a GSD of 8 for the entire area of the skin. This approach is used by NIOSH as 

a means to deal with the fact that the baseline risk of cancer imbedded in IREP is the baseline 

risk of cancer for the entire area of the skin, not just the baseline risk for skin on the head, neck, 

and hands. For example, Table 2 of NIOSH 2002 presents the excess relative risk (ERR)1of 

skin cancer per Sv and Table 3 presents the age-adjusted skin cancer incidence. Given this 

 

1 Excess relative risk (ERR) is the ratio of the excess risk of a specified stochastic effect to the probability 

of the same effect in the unexposed population, i.e. the relative risk minus one. In theory, this should be equal to the 

attributable risk from the exposure received by the exposed group, but ERR is normally used in the context of 

observed numbers of effects, whereas attributable risk normally refers to a figure calculated on the basis of a known 

or estimated exposure.
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understanding, we have the following questions. If IREP did include the baseline risk to the 

head, neck, and hands, wouldn’t that baseline risk be lower than the baseline risk attributed to the 

entire area of the skin? Also, if the baseline risk is lower, doesn’t that mean that the POC would 

increase, as derived using the above equation? Further, if IREP included the baseline risk for the 

head, neck, and hands, it would not be necessary to reduce the dose, resulting in a considerably 

higher POC. 

We believe that these are reasonable questions, because page 8 of NIOSH 2002 states that skin 

dose should be calculated for the location where the skin cancer occurred, and, if the body 

location is unspecified, the maximum skin dose at any location should be used as input to IREP.

7.0 CONCERNS RELATED TO NIOSH’S DOSE MODEL FOR LARGE URANIUM 

FLAKES ON SKIN

Assuming that this exposure scenario is plausible, at least for some AWE facilities in the early 

years, we have the same basic questions as described above, except now we are dealing with a 

very small area, perhaps 1 cm2, and relatively high dose rates (e.g., 240 mrem/hr). In this case, it 

seems that the baseline risk should be expressed in terms of ERR per Sv per cm2for the general 

area where the exposure might have occurred. We acknowledge that this issue is complicated by 

the fact that in most circumstances, where a person is diagnosed with a cancer on an exposed 

area, there is likely no evidence that a localized exposure had, in fact, occurred, except to the 

extent that we might consider it plausible that such an exposure could have occurred given the 

operational circumstances at the time. We further acknowledge that we have no way of knowing 

how often such events occurred or how long the particle remained on the skin before it was 

washed off. Nevertheless, we believe that this subject merits some discussion.

8.0 REFERENCES

42 CFR Part 81. 2002. Guidelines for Determining the Probability of Causation Under the 

Energy Employees Occupational Illness Compensation Program Act of 2000; Final Rule;

Department of Health and Human Services. May 2002.

Heatherton, R.C., 1960. Estimation of Depth Dose from UX2 Beta Rays.

NIOSH (National Institute for Occupational Safety and Health) 2002. “NIOSH-Interactive 

RadioEpidemiological Program (NIOSH-IREP) Technical Documentation,” Final Report. June 

18, 2002.

ORAUT 2004. Technical Basis Document for the Fernald Environmental Management Project 

– Occupational External Dose, ORAUT-TKBS-0017-6, Rev. 00. Oak Ridge Associated 

Universities Team, Cincinnati, Ohio. April 20, 2004.

ORAUT 2005. Interpretation of Dosimetry Data for Assignment of Shallow Dose, ORAUTOTIB-0017, Rev. 01. Oak Ridge Associated Universities Team, Cincinnati, Ohio. October 11, 

2005.
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ORAUT 2013. Technical Basis Document: An Exposure Matrix for Bridgeport Brass: Havens 

Laboratory and Adrian Plant, ORAUT-TKBS-0030, Rev. 01. Oak Ridge Associated 

Universities Team, Cincinnati, Ohio. January 24, 2013.

Thomas, J.M., and R.S. Bogard, 1994. Technical Basis for Beta Skin Dose Calculations at the 

Y-12 Plant, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee. March 1994. (SRDB 19821)

[Redact] 2000. U.S. Army, Aberdeen Proving Grounds, Maryland, personal communications 

(e-mail) on February 8, 2000.

PHS (U.S. Public Health Service), 1970. Radiological Health Handbook, Rockville, Maryland.

SC&A 2000. “Reassessment of Acute Radiation Doses Associated with BRAVO Fallout,”

Prepared by Hans Behling, John Mauro, and Kathleen Behling of S. Cohen & Associates for

William Graham, Public Advocate, Nuclear Claims Tribunal, Republic of the Marshall Islands,

May 2000.

Sharp, R., and W.H. Chapman, 1957. Exposure of Marshall Islanders and American Military 

Personnel to Fallout, Operation CASTLE, Project 4.1 Addendum, Naval Medical Research 

Institute, Report #WT-938 EX (March 1957). Online at 

http://worf.eh.doe.gov/data/ihp2a/0283_a.pdf.
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APPENDIX A: EXCERPT FROM THE REPORT, REASSESSMENT OF ACUTE

RADIATION DOSE ASSOCIATED WITH BRAVO FALLOUT

Prepared by Hans Behling, John Mauro, Kathleen Behling,

May 2000 for the Nuclear Claims Tribunal, Republic of the Marshall Islands

4.1.5 Additional Radiation Doses Associated with External Body Contamination

Fallout deposited on skin, clothing, and hair of the Marshallese represents a complex mixture of 

radionuclides that emit alpha, beta, and gamma radiations of variable energies. Depending on 

the type of emission, radiation exposure may include the entire body or only select tissues. 

Alpha-emitting radionuclides with their extremely short range in tissue would pose little or no 

harm as long as they remained outside the body. With the limited range of most beta particles, 

the primary concern for external exposure is the dose that may be received by the skin. 

However, if skin contamination includes highly energetic betas [e.g., yttrium-90 releases betas 

with an average energy of 0.90 MeV and a maximum energy of 2.27 MeV (PHS 1970)], tissues 

just below the skin such as the thyroid gland may also be exposed. For the radionuclide mix 

associated with BRAVO, the penetrating beta component was illustrated in the Sharp and 

Chapman Report (1957) by the following passage (p. 31), which refers to the observation made 

by U.S. Service personnel on Rongerik:

“Men at the radiostation collected fallout material. This material when placed on 

the surface of a cathode-ray tube (part of ionosphere equipment), caused that 

portion of the tube to glow.” [Emphasis added.]

Dose Rate Measurements of External Contamination

The 1957 Report by Sharp and Chapman provides a substantial body of data pertaining to 

contamination of the Rongelapese that had been evacuated. Chapter 4 of their Report provides a 

timeline for decontamination efforts and Chapter 5 summarizes physical measurements of 

residual contamination at various times.

The 16 Marshallese who had been evacuated by plane arrived at Kwajalein at noon on 3 March 

(i.e., H+55 hours). Upon arrival, these individuals showered and bathed several times in an 

emergency decontamination area.

The 66 Marshallese evacuated by destroyer (48 from Rongelap and 18 from Ailinginae) had 

taken several showers and “. . . prolonged washings with salt-water hose sprays while aboard the 

destroyer that was enroute to Kwajalein.

Survey Instrument Used to Assess Contamination

The instrument used to survey Marshallese for body contamination was the AN/PDR-27c, a 

standard military issue that was in general use at the time. The AN/PDR-27c is a beta/gamma 

survey meter that used two Geiger-Mueller tubes in a single probe. It was powered by 6 D-cell 
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NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82.

batteries and could be operated at four scales with the following ranges: 0–0.5; 0–5; 0–50; and 

0–500 mR/hr. The AN/PDR-27c has been replaced in the Army by the AN/VDR-2, but can still 

be found in the National Guard ([Redact] 2000).

The most highly contaminated areas of the body were the head and areas of the skin not 

protected by clothing. Natural folds of the skin and areas of the skin where perspiration 

accumulated were also found to have elevated levels of contamination. A particular problem for 

decontamination was the hair/scalp areas since Marshallese used a coconut-oil hair dressing.

Table 4.1-10 summarizes “contamination measurements” taken on 3 March. Columns #2, #3, 

and #4 cite dose rate measurements in behalf of 15 of the 16 persons evacuated by plane. Data in 

column #2 provide the most useful information, since these readings were taken before there 

were any attempts to decontaminate personnel and, therefore, provide a technical basis for 

assessing residual skin contamination levels at about H+55 hours. The average “dose rate” 

readings for the 15 persons monitored for contamination corresponds to about 175 mR/hr. After 

two successive showerings, average dose rate readings on 3 March were reduced to 51 mR/hr 

and 31 mR/hr, respectively, for these individuals.

Columns #6, #7, and #8 identify a single dose rate reading on 3 March for each of 52 persons 

who were among the 66 persons evacuated by destroyer (U.W. Phillip). For these individuals, 

the average 3 March reading was 19 mR/hr. However, it must be recalled that these individuals 

had previously been subjected to decontamination efforts aboard the destroyer that included 

several salt-water hosings and showering. For this reason, contamination levels for all evacuees 

at H+55 hours will assume the average value 175 mR/hr that had been determined prior to the 

first showering for the 15 individuals who were evacuated by plane.

Contaminated Clothing. Contaminated clothing that had been worn by the 15 Marshallese who 

had been evacuated by plane was sequestered but had not been laundered. When surveyed, these 

articles of clothing still yielded dose rate readings of about 100 mR/hr on 18 March. The Report 

states that “. . . Repeated washings by Kwajalein laundry failed to lower the counts appreciably. 

The addition of citric acid to laundry water facilitated decontamination.” On the basis of the 

standard decay formula, the dose rate reading of clothing at H+12 hours (H+12 hours 

approximates the end of fallout on Rongelap) would have corresponded to about 7,400 mR/hr.
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Table 4.1-10. Contamination Measurements of Individual Evacuees from Rongelap and

Ailinginae by Means of Radiac Set No. AN/PDR-27c Survey Instrument 

(Readings in mR/hr)

Data for 15 Rongelapese Evacuated by Plane Data for Rongelapese Evacuated by Destroyer

Individual

Before 1st 

Shower

2nd 

Reading

3rd 

Reading Individual Reading Individual Reading

#1 200 30 12 #1 22 #27 22

#2 200 25 20 #2 20 #28 15

#3 80 70 45 #3 25 #29 10

#4 80 30 20 #4 20 #30 12

#5 200 80 40 #5 34 #31 40

#6 200 10 --- #6 10 #32 10

#7 200 20 15 #7 10 #33 15

#8 100 30 10 #8 40 #34 30

#9 200 30 25 #9 10 #35 25

#10 80 70 70 #10 30 #36 30

#11 80 50 20 #11 27 #37 10

#12 200 100 50 #12 10 #38 5

#13 200 100 30 #13 27 #39 20

#14 200 100 60 #14 15 #40 10

#15 400 20 15 #15 25 #41 10

#16 15 #42 10

#17 20 #43 24

#18 12 #44 30

#19 20 #45 15

#20 23 #46 25

#21 34 #47 35

#22 20 #48 5

#23 10 #49 7

#24 24 #50 5

#25 16 #51 27

#26 25 #52 15